Problem: $-\dfrac{2}{4} - \dfrac{6}{10} = {?}$
Explanation: $ = - {\dfrac{2 \times 5}{4 \times 5}} - {\dfrac{6 \times 2}{10 \times 2}} $ $ = - {\dfrac{10}{20}} - {\dfrac{12}{20}} $ $ = - \dfrac{{10} - {12}}{20} $ $ = -\dfrac{22}{20}$